A Discrete Shared Processor Model for DQDB

Abstract The Distributed Queue Dual Bus (DQDB) protocol is being considered by the IEEE 802.6 and ANSI T1S1.1 as an important component in their Metropolitan Area Networks (MAN) and Broadband ISDN User Network Interface (BISDN-UNI) standards respectively. The DQDB protocol is modelled in this paper by a discrete time multi-priority multiqueue system involving several distributed stations and a central shared processor. Exact analysis for the model yields an expression for the mean packet delay as a function of the packet size for each priority. Comparison with simulation results demonstrates that the model can accurately describe DQDB where transmitting stations on the same bus are concentrated.